Motion in a Plane
Class 11 · Motion in a Plane
Cross Product (Vector)
|A×B| = |A||B|sinθ — parallelogram area and right-hand rule direction.
Key Notes
01
|A × B| = |A||B| sinθ — a vector.
02
Direction: right-hand rule, perpendicular to both A and B.
03
|A × B| equals the area of the parallelogram formed by A and B.
04
A × B = −(B × A). A × A = 0.
05
Torque τ = r × F; angular momentum L = r × p — both are cross products.
Formulas
Cross product magnitude
Magnitude equals parallelogram area.
Determinant form
Component formula via 3×3 determinant.
Important Points
Parallel vectors give zero cross product — useful to detect parallelism.
Cross Product (Vector) notes from sciphylab (also known as SciPhy, SciPhy Lab, SciPhy Labs, Physics Lab). Class 11 physics revision for JEE Mains, JEE Advanced, NEET UG, AP Physics 1/2/C, SAT, and CUET-UG.